摘 要
近年來，煙霧警報器已是室內安全不可或缺的重要裝置，法律已明文規定其為各類場所的配置標準，然而市面上許多煙霧警報器並不適用於水氣較高的場所，例如廚房與浴室等，因烹飪的蒸氣或水霧可能引起煙霧警報器的誤報，倘若使用者因誤報率高而關閉警報器，恐提高重大災害的發生率。另外，因室內光源會干擾一般的煙霧警報器，導致感測器光訊號之訊號雜訊比（SNR）較低。因此，本論文提出基於混合式調變光通訊與特定光波長元件實現之水霧與煙霧判別感測系統，此系統在元件與電路層面實現了抗室內光源干擾，並利用特別選用的帶通型光檢測器結合光通訊混合調變演算法，進一步增加訊號雜訊比。此外，根據煙霧的光學特性，透過特定多波長帶通型光感測陣列來準確判斷煙霧和水霧，從而降低系統的誤報率。
關鍵詞：煙霧感測、光散射、混合調變、訊號雜訊比、帶通光檢測器 Abstract
In recent years, smoke detectors have become indispensable indoor devices, with regulations mandating their installation in various premises. However, many smoke detectors available on the market are not suitable for environments with high humidity, such as kitchens and bathrooms. Steam or smoke generated during cooking can trigger false alarms in smoke detectors, and frequent deactivation of alarms due to high false alarm rates may increase the risk of major disasters. Additionally, conventional smoke detectors are susceptible to interference from indoor lighting sources, resulting in a lower signal-to-noise ratio (SNR) of optical signals. To address these challenges, this study proposes a discrimination and sensing system for water mist and smoke based on an optical communication with hybrid modulation technique using specific wavelength components. This system implements resistance to the light interference of indoor sources at both the component and circuit levels. It further enhances the SNR with a selected bandpass optical detector combined with a hybrid modulation algorithm for optical communication. Furthermore, leveraging the optical characteristics of smoke, a specific multiwavelength bandpass optical sensing array is employed to accurately distinguish between water mist and smoke, thereby reducing the rate of false alarm for the proposed system.
Keywords: Smoke sensing, Light scattering, Hybrid modulation, Signal-to-noise ratio, Band-pass optical detector